It took 2½ years. It cost $425 million. It required demolishing the Dorset Hotel on West 54th Street (top left) piece by piece and erecting a new structure in its place. All the while, New York got to watch the making of this work of art: the new Museum of Modern Art (right), which reopens Nov. 20.

Yoshi Taniguchi, MoMA’s modest Japanese architect, likes to compare his museums to teacups. His latest work is admirable, maybe, but not as beautiful as the tea (that is, the art) it contains.

The man from Union Square (and four other of the city’s favorite restaurants) will oversee the Modern – the museum’s 95-seat, fine-dining destination and bar, complete with Danish tableware from MoMA’s permanent-design collection and Atelier chef Gabriel Kreuther at the helm – as well as a cafeteria and a dessert café.

All told, they might make that new $20 admission fee a bit easier to swallow.

But on opening day, MoMA is free to all – the better to appreciate its soaring atrium, enormous skylights, restored Bauhaus stairs and the altogether remarkable renovation at 11 W. 53rd St.

Those who’ve missed Monet’s “Water Lilies” will find them again, in the museum’s atrium, while Van Gogh’s “Starry Night” shines on the fifth floor amid a constellation of other works from that period.

The Abby Aldrich Rockefeller Sculpture Garden is back, too – with 31 large-scale sculptures by the likes of Picasso, Rodin and Giacometti.

And then there are the works no MoMA-goer has ever seen there before: several newly acquired pieces the museum is just now putting on display.

Look for Picasso’s “Pregnant Woman,” painted when his companion Francoise Gilot gave birth to their daughter – the future jewelry designer Paloma Picasso.

Watch, too, for contemporary artist Jeff Wall’s “Invisible Man,” a large-scale re-creation of the cellar room – “Warm and full of light,” since it’s lit by 1,369 light bulbs – that Ralph Ellison wrote about in his landmark novel.

But the brightest light of all is bound to come from those enormous skylights and huge windows, which look out over sculpture, brownstones and sky. MoMA director Glenn Lowry likes to call it “a laboratory for looking at art.”